Highly contoured, multi-leg structures having high strength and lightweight may be used in various applications, such as in aerospace vehicles. For example, aerospace frames, spars, ribs, stringers and similar structures, may have multiple legs which are contoured along the length of the structure. Fabricating such highly contoured structures from composite materials is challenging, and thus is largely limited to hand layup techniques which are not only labor intensive, but may not be well suited for high production volume applications. Automatic fiber placement (AFP) machines may be used to fabricate some forms of composite structures, however these machines may not be efficient for producing highly contoured, multi-leg structures with tight radii, in part because the more complicated structural features of these structures may require the machine to start and stop, as well as change directions relatively frequently. Moreover, certain structure configurations, such as those containing a Z or a J-cross section, may not be fabricated using AFP machines because they may not be able to load material at the inside corners of these structures.
Accordingly, there is a need for a method of fabricating contoured, and especially highly contoured, continuous composite structures containing multi-leg features that meet high performance specifications in a high volume production environment.